Endocrine Abstracts

Background: Thiol/disulfide homeostasis plays an important role in antioxidative defense mechanism, detoxification, signal transport, management of enzyme activity and trascription factors, and apoptosis. When thiol/disulphide homeostasis breaks down, these important cellular functions get deranged. Pathologies secondary to oxidative stress are seen in organeles in which this homeostasis is deranged. The aim of the study was to investigate dynamic thiol/disulfide homeostasis in newly diagnosed type 2 diabetes mellitus.

Materials and methods: Blood thiol/disulfide homeostasis status, that consists of native thiol–disulphide exchanges, was investigated in 60 patients (22 males and 38 females) diagnosed with type 2 diabetes mellitus and 60 healthy control subjects (25 males and 35 females). Serum native thiol and total thiol concentrations were measured as a paired test. The half of the difference between total thiol and native thiol concentrations gave the disulphide bond amount.

Results: In comparison to the control group, patients with diabetes mellitus had lower levels of serum thiol and total thiol (340.7±46.1 μmol/l vs 313.7±57.4 μmol/l; P=0.005 and 366.7±46.7 μmol/l vs 343.7±59.0 μmol/l; P=0.020 respectively) while higher average disulfide level (12.9±3.2 μmol/l vs 15.0±4.6 μmol/l; P=0.008). In patients with diabetes mellitus, average disulfide/thiol ratio (%) (3.9±1.2 vs 5.0±1.6; P=0.001) and disulfide/total thiol ratio (%) (3.6±1.0 vs 4.5±1.6; P=0.001) was higher while average thiol/total thiol ratio (%) was lower (92.8±2.1 vs 91.0±3.4; P=0.001) than the control group. HbA1c level and age correlated positively with serum disulfide/thiol ratio and disulfide/total thiol ratio (r=0.239, P=0.009 and r=0.228, P=0.012 respectively) while thiol/total thiol ratio was correlated negatively (r=−0.228, P=0.012).

Conclusion: A tendency towards disulfide formation in thiol/disulfide homeostasis was found in patients with diabetes mellitus and there was a positive correlation between HbA1c and disulfide/thiol ratio.